package com.serverlet;

import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.nio.charset.StandardCharsets;
import java.util.Map;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import javax.servlet.http.HttpServletResponse;

/**
 * 统一编码
 *
 * @author ckc
 */
@WebFilter(filterName = "EncodingFilter", urlPatterns = "/*")
public class EncodingFilter implements Filter {

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        // TODO Auto-generated method stub

    }

    @Override
    public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws IOException, ServletException {
        //1.强转
        HttpServletRequest request = (HttpServletRequest) req;
        HttpServletResponse response = (HttpServletResponse) resp;
        //System.out.println("@@@@@@@@@@@@@@@@@@");
        //2.放行
        chain.doFilter(new MyRequest(request), response);
    }

    @Override
    public void destroy() {
        // TODO Auto-generated method stub

    }

}


/**
 * 之前的MyRequest增强了request.getParameter("name");方法
 * 增强了所有的获取参数的方法request.getParameterValues("name");
 * 增强了所有的获取参数的方法request.getParameterMap();
 */
class MyRequest extends HttpServletRequestWrapper {
    private HttpServletRequest request;
    private boolean flag = true;


    public MyRequest(HttpServletRequest request) {
        super(request);
        this.request = request;
    }

    @Override
    public String getParameter(String name) {
        if (name == null || name.trim().length() == 0) {
            return null;
        }
        String[] values = getParameterValues(name);
        if (values == null || values.length == 0) {
            return null;
        }

        return values[0];
    }

    @Override
    /**
     * hobby=[eat,drink]
     */
    public String[] getParameterValues(String name) {
        if (name == null || name.trim().length() == 0) {
            return null;
        }
        Map<String, String[]> map = getParameterMap();
        if (map == null || map.size() == 0) {
            return null;
        }

        return map.get(name);
    }

    @Override
    /**
     * map{ username=[tom],password=[123],hobby=[eat,drink]}
     */
    public Map<String, String[]> getParameterMap() {

        /**
         * 首先判断请求方式
         * 若为post  request.setchar...(utf-8)
         * 若为get 将map中的值遍历编码就可以了
         */
        String method = request.getMethod();
        if ("post".equalsIgnoreCase(method)) {
            try {
                request.setCharacterEncoding("utf-8");
                return request.getParameterMap();
            } catch (UnsupportedEncodingException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        } else if ("get".equalsIgnoreCase(method)) {
            Map<String, String[]> map = request.getParameterMap();
            if (flag) {
                for (String key : map.keySet()) {
                    String[] arr = map.get(key);
                    //继续遍历数组
                    for (int i = 0; i < arr.length; i++) {
                        //编码
                        arr[i] = new String(arr[i].getBytes(StandardCharsets.ISO_8859_1), StandardCharsets.UTF_8);
                    }
                }
                flag = false;
            }
            //需要遍历map 修改value的每一个数据的编码

            return map;
        }

        return super.getParameterMap();
    }

}
